Fluorophenols are useful intermediates for the manufacture of various industrial products including dyes, agricultural pesticides and lubricants. For example, o-fluorophenol may be chlorinated or brominated to 2-fluoro-4-chlorophenol or 2-fluoro-4-bromophenol, respectively, for use in preparing ((fluorophenoxy)phenoxy)propionate herbicides as described in U.S. Pat. No. 4,550,192.
Conventional methods of preparing fluorophenols have been based on diazotization routes which involve a series of steps. In British Patent No. 1,433,455, for example, fluorophenols were prepared by (a) diazotizing a fluoroaniline, and (b) decomposing the diazonium salt in the presence of water.
Alternatively, fluorophenols have been prepared by the hydrolysis of the corresponding halofluorobenzenes; see, for example, U.S. Pat. No. 2,950,325, British Patent No. 850,888, Russian Patent No. 143,404, and G. G. Yakobson et al. in Dokl. Akad. Nauk SSSR, 141, 1395 (1961) and in Zh. Obshch. Khim., 34, 932 (1964). Typically, these hydrolysis reactions are conducted under basic conditions in the presence of a copper catalyst. Yields are particularly dependent on competing reactions such as reduction and diphenyl ether formation. For all practical purposes, the preparative value of the hydrolysis reaction is limited to bromo derivatives, with the corresponding chlorofluorobenzenes giving little if any product under comparable conditions.